* There are many "Catherines" in this game. In this guide, "Catherine" refers any one of the four types of robot Catherine while "Catherine Torsche" refers to the human Catherine.

Go to any major town to trigger the quest mail automatically.

Go to F4 of Torsche Mansion Grand Library and walk over the middle of the room to trigger a non-combat instance.

Click on the green arrow leading to Dr. Torsche's Laboratory to start another non-combat instance. Within the mission, talk to Catherine.

With Catherine as team leader, go to D2 of Torsche Mansion Savage Garden and click on the green arrow leading to Torsche Mansion Basement to start a combat instance. The mission lasts for 1 hour. Catherine must not die in the mission; if she dies, it is instant Mission Failure without any chance for Soul Crystal or Resuscitation. Within the mission:-

Move a few steps closer to the central room before buffing. The first room will be filled up with Rotating Blades after a few minutes.

Defeat normal mobs while waiting for Catherine Torsche to appear. Mobs are lvl120 Lifeless with 60 AR/DR. There are 4 stairwells to the sides of the central room that serve as safe zones, so stay at those spots to avoid getting swarmed.

After some time, Catherine Torsche will appear after a short cutscene.

Look for her, or stay at a stairwell and wait for her to look for you. Either way, reduce Catherine Torsche's hitpoints to critical level to trigger a second cutscene. Catherine Torsche has the following stats:-
Catherine Torsche (lvl130)
human / light / none / small
hp: 4,814,544
AR / ATK: 67 / 3697
DR / DEF: 67 / 172
RES: 50 all

Return to Dr Torsche's Laboratory and talk to Dr. Torsche to receive Catherine Torsche Character Card.

This marks the end of Catherine Torsche's recruitment quest. Completion is required for the Torsche Mansion Basement raid mission in v4.5.

This mission has a generous time-frame, so it is a little bit easier compared to the fight against Reckless Emilia. The real challenge is in keeping Catherine alive in a sea of lvl120 mobs for the entire mission. There are several ways to do this. I'll describe them below. Once again, Catherine must not die at all within the mission. There is absolutely no chance to recover with Soul Crystal or Resuscitation. If Catherine dies, it is instant Mission Failure.

Do not bother with Invisible Potions for this mission, as the normal mobs can see right through the effect. Do not bring more than one Catherine into the mission, as the mission will fail if any one of your Catherines dies.

The normal mobs in this mission are all 60 AR/DR Lifeless consisting of Llyod, Walter, Helena, and Sasha, as well as three new mob types Gwraig, Pyg, and Wight. Gwraig is the scythe-wielding Helena-lookalike, Pyg is the mishappened spiderling creeper, and Wight is the witch. Both Pyg and Wight spam their AoE knockback skills a lot, so killing them should be the priority.

For the first half of the mission, keep clearing mobs until Catherine Torsche appears. The spawn time of Catherine Torsche is apparently affected by kill-count, so try to clear the mobs as quickly as possible. Gwraig will speak different lines at interval, so you will know you are doing the right thing. Montoro and Catherine Torsche will interrupt with a cutscene shortly after Gwraig speaks all 3 of her lines.

Once she has spawned, Catherine Torsche will patrol the area to locate you, so it's not actually necessary to seek her out actively. Make sure your Visual Effects are turned on so that her blue aura shows, otherwise she can be hard to spot among the larger normal mobs.

Catherine Torsche has a couple of skills that comes with rapid SP and HP drain effects. These statuses can be removed instantly with Enhanced Antidote. The Enhanced Antidote is a new and common item drop from normal mobs in Dr Torsche Mansion, and you may want to farm 20 or so of these before attempting the mission. Or if you can't be bothered, then just keep potting until the statuses wear off.

Other than that, she's not too difficult, so just keep chipping away her health and she will surrender soon enough.

Now, on keeping your own Catherine alive. The method to use depends on the type and level of your Catherine. These methods are by no means the only methods available, so if these don't work for you, then feel free to experiment with your own solutions.

High Level Catherine
If your Catherine is high level and well-equipped enough to be played as a normal character, then there isn't much to worry about. Just stay near a stairwell and clear the surrounding mob until Catherine Torsche appears. Once you have Catherine Torsche's attention, you can retreat deep into the stairwell to fight her with minimal disturbances from the normal mobs. If you can get your Catherine to 62~65 DR once fully buffed, then she can be considered high level enough.

Veteran Catherine
(For the average player, this is the safest way to go through the mission. A veteran level Catherine will have enough DR and HP to absorb a few hits from both normal mobs and Catherine Torsche, so there's less chance of mission failure.) A veteran combat-type Catherine can survive rather well with a good shield and some good armour. A summoner-type Catherine will have to be a little more careful. They will get overwhelmed by the normal mobs easily, so just leave them deep inside the safety of a stairwell while your main characters fight outside. Catherine Torsche has some AOE attacks, so it's even more important to keep your own Catherine out of the way.

Low Level Combat-type Catherine
(Thanks to SHINE for coming up with this. ^-^ For relatively well-equipped players, this is by far the easiest way to get past the mission.) It's possible to avoid getting hit by the Rotating Blades in the starting room by sticking as close to the wall at the back as possible, so just put your Catherine on Kneeling Shot and leave her there. Your other two characters should then guard the entrance at the other end to prevent the normal mobs from straying inside the room and attacking your Catherine. The purpose of Kneeling Shot is to prevent your Catherine from moving. This method works if your main attackers are capable of surviving the normal mob swarm out in the open, so they need about 62~65 DR once fully buffed.

Low Level Summoner-type Catherine
A low level Catherine will most certainly die to any normal mob attack in one hit. The previous method will not work for a summoner-type because she will automatically move towards on your main characters once they are too far apart. To get past the mission with a low level summoner, you will need a whole lot of luck and some very good equipment. It's possible to run towards a stairwell at the beginning of the mission without getting hit by the normal mobs, but your characters, including your Catherine, will unavoidably attract lots of aggro. Once at a stairwell, place your Catherine deep inside and clear all the trailing mobs as quickly as possible before they hit your Catherine. If you manage to do this successfully, then you can play the rest of the mission as per normal. Some mobs might stray inside the stairwell occasionally, so keep a sharp lookout.